My 04 TSX electrical system have been messing with me for two days: every hour or so the radio, the dashboard and headlights would go off than come with after a fraction of a second. It seemed to be happen more often if I had a gadget (bluetooth or GPS) plugged into 12V outlet.

Then yesterday the car stalled at a traffic light. It restarted with no problems but the CEL light came on. This morning Autozone pulled P0685 code from it - ECM/PCM power control malfunction or open/short circuit. After 5 miles the CEL light turned off by itself.

I left the car running, shook and massaged every wire I could reach under the hood and around the fuse box and it ran all the time without the hiccups. Any ideas where I can do more troubleshooting?

thanks!

 

Sergey, I have no doubt that the very talented and smart folks around here will know more than I do, but I thought I'd at least give you some immediate tips. It can't hurt, and they're cheap or free.

- Completely remove your battery terminal cables and use a wire brush to scrub the terminals and the cables. Reinstall cables and firmly tighten and apply battery terminal grease (available in a $.99 packet at auto parts stores).

- Check/tighten the ground from the negative battery cable to the car. Clean this with a wire brush as well. With the "open circuit" thing, it just may be a grounding issue.

- I can't recall all of the ground connections (black wire bolted to the metal of the car) I found while cleaning my engine bay, but I know there are two on the left side. One is below/around the alternator, and the other one is also in the (very) general area. Try a search or ask someone with a Helms or OEM Service Manual to guide you to where the ground connections are. Anyway, wire-brush those and tighten if needed.

- Check the battery fuse (unplug the battery first). You'll need an inexpensive multimeter if don't already have one.

- Perhaps the 12v outlet has a loose connection. Search around here for "console light" or "remove console" to find a step-by-step guide for how to do it. I just changed my shift gate bulb (PRND) bulb, and while it was apart, I tightened all my connections, including the 12v outlet ones. There's a stiff little plug that plugs into the back of those outlets, and if it has wiggled loose, re-seating it might just help.

- Do you have an aftermarket audio system? I know on my previous cars, I've had flaky electrical problems. In hindsight, it was likely the equipment or the installation of it that caused those issues. If so, that might be a clue, too.

- Lastly, it might be the alternator. I'd try the other things first, though, and see if that helps.

 

Thanks for your detailed reply, I will try all these things.

More info: I don't have an aftermarket audio system and I have not done any mods to the car recently. 4 days ago I took it for TX state inspection and oil change.

 

Having just gone through a bunch of crap with my wife's Protege5, similar stuff to yours but without the CEL code, it turned out to be a flaky alternator that killed (didn't charge) the battery, which caused all kinds of weird problems (stalling, lights flickering, idiot lights on dash randomly coming on (such as ABS, parking brake, airbag, etc...)).

If you have a multimeter, check the voltage across the battery terminals with the car off (12.5 volts or so), and on (14.4 volts or so). If the on and off voltages are very similar, around 12v, then your alternator is going kaput and you should look into getting that checked out / tested / rebuilt / replaced w/ rebuilt, etc.

 

They can also test your alternator at AutoZone, if you don't have the multimeter.

 

Of the symptoms, I would say 90% cause is a bad ground.

 

i've had this problem earlier this summer. its a bad ground connection. best bet is to replace the ground/negative battery cable. go to autozone and buy it for 5bucks. after i replaced it i've never had the problem again.

 

Thanks, everybody, for your advice. I bought a wire brush and cleaned the battery terminals and both cables. It has been a week and so far the car runs fine. Keeping my fingers crossed.

 

 

Yeah, uber-clean battery terminals and posts are essential. I guess I could have mentioned that earlier, eh?

 

Put a little terminal grease on the terminals to help prevent future corrosion. I swear I saw someone suggest Vaseline once, but I'm not sure about that. Worst case, auto parts stores sells little packets for $1.

 

Vaseline works well for that actually... its petroleum-based, doesn't wash off easily, and keeps moisture off of the terminals.

Did you know that regular Coca Cola will clear a battery terminal of all corrosion?